Introduction
This document explains how to use the xmodem command at the console to download Cisco IOS® software
using the ROM monitor (ROMmon).
Prerequisites
Requirements
There are no specific requirements for this document.
Components Used
The information in this document is based on these software and hardware versions:
· Cisco 827, 1600, 1700, 2600, 3600, and 3700 Series Routers
· Cisco AS5200, AS5300, AS5350, and AS5400 Universal Access Servers
Note: Xmodem can also be used on certain Catalyst switches.
The information in this document was created from the devices in a specific lab environment. All of the
devices used in this document started with a cleared (default) configuration. If your network is live, make sure
that you understand the potential impact of any command.
Conventions
Refer to Cisco Technical Tips Conventions for more information on document conventions.
Overview
Xmodem can be used on a group of routers (see Components Used) and is used in disaster recovery situations
where the router has no valid Cisco IOS software or bootflash image to boot from and hence, only boots up in
ROMmon. This procedure can also be used where there are no Trivial File Transfer Protocol (TFTP) servers
or network connections, and a direct PC connection (or through a modem connection) to the router's console
is the only viable option. Because this procedure relies on the console speed of the router and the ****** port of
the PC, it can take a long time to download an image. For example, downloading Cisco IOS Software Release
12.1(16) IP Plus image to a Cisco 1600 Series Router using a speed of 38400 bps takes approximately 25
minutes.
Usage
Here is the command syntax for xmodem as per the Command Reference Manual for Cisco IOS version 12.2.
xmodem [−c] [−y] [−e] [−f] [−r] [−x] [−s data−rate]
This table describes the command syntax for the xmodem command.
syntax
Description
−c
(Optional) CRC−16 checksumming, which is more
sophisticated and thorough than standard
checksumming.
−y (Optional) Uses the Ymodem protocol for higher
throughput.
−e
(Optional) Erases the first partition in Flash
memory before starting the download. This option
is only valid for the Cisco 1600 series.
−f
(Optional) Erases all Flash memory before starting
the download. This option is only valid for the
Cisco 1600 series routers.
−r (Optional) Downloads the file to DRAM. The
default is Flash memory.
−x (Optional) Does not execute the Cisco IOS software
image on completion of the download.
−s
data−rate
(Optional) Sets the console port's data rate during
file transfer. Values are 1200, 2400, 4800, 9600,
19200, 38400, and 115200 bps. The default rate is
specified in the configuration register. This option
is only valid for the Cisco 1600 series routers.
filename
(Optional) Filename to copy. This argument is
ignored when the −r keyword is specified since
only one file can be copied to DRAM. On the Cisco
1600 series routers, files are loaded to the
ROMmon for execution.
Note: xmodem options e, f, and s are only supported on the Cisco 1600 Series Routers. In order to find out
the syntax and available options to use with the xmodem command, enter xmodem −? at the ROMmon
prompt.
Here is an example of the xmodem command issued on a Cisco 1603 Router:
rommon 9 >xmodem −?
usage: xmodem [−cyrxefs]<destination filename>
−c CRC−16
−y ymodem−batch protocol
−r copy image to dram for launch
−x do not launch on download completion
−f Perform full erase of flash
−e Perform erase of first flash partition
−s<speed>Set speed of Download, where speed may be
1200|2400|4800|9600|19200|38400|115200
Here is an example of the xmodem command issued on a Cisco 2620 Router:
rommon 1 >xmodem −?
xmodem: illegal option −− ?
usage: xmodem [−cyrx] <destination filename>
−c CRC−16
−y ymodem−batch protocol
−r copy image to dram for launch
−x do not launch on download completion
Examples
rommon 12 > xmodem −cfs115200 c1600−sy−mz.121−16.bin
rommon 2 > xmodem −c c2600−is−mz.122−10a.bin
Notes:
The xmodem transfer only works on the console port. You can only download files to the router. You
cannot use xmodem to get files from the router.
·
It is also important to note that the −sdata−rate option is only available on the Cisco 1600 Series
Routers and was implemented to overcome the console baud rate limitation of 9600 bps. If you
specify −sdata−rate of 115200 bps for example, you can increase the download rate and hence, reduce
download time. Other Cisco routers support console speeds up to 115200 bps. Therefore, the
−sdata−rate option is not required.
·
Ensure that the PC ****** port is using a 16550 universal asynchronous transmitter/receiver (UART) if
you are downloading a Cisco IOS software image through the router's console speed at 115200. If the
PC ****** port is not using a 16550 UART, it is recommended that you use a speed of 38,400 or lower.
·
Xmodem Procedure for Downloading a Cisco IOS Software
Image onto a Cisco 1603 Router
Use this xmodem procedure in order to download a Cisco IOS software image onto a Cisco 1603 Router.
Launch a terminal emulator program.
In this example, configure Windows HyperTerminal for 8−N−1 at 9600 bps and connect your PC's
****** port to the console port of the router. Once connected, you need to get into the ROMmon
prompt (rommon 1>). Typically, if the router's Cisco IOS software image and bootflash image are
both corrupt, the router only comes up in ROMmon mode. If the former is not true and you need to
get into the ROMmon prompt, you need to change the configuration register (typically 0x2102 as
given by show version) to 0x0:
1600#configure term
Enter configuration commands, one per line. End with CNTL/Z.
1.
1600(config)#configure
1600(config)#config−register 0x0
1600(config)#^Z
1600#
00:22:06: %SYS−5−CONFIG_I: Configured from console by console
1600#reload
System configuration has been modified. Save? [yes/no]: n
Proceed with reload? [confirm]
00:22:16: %SYS−5−RELOAD: Reload requested
System Bootstrap, Version 12.0(3)T, RELEASE SOFTWARE (fc1)
Copyright (c) 1999 by cisco Systems, Inc.
Simm with parity detected, ignoring onboard DRAM
C1600 platform with 16384 Kbytes of main memory
rommon 1 >
From the ROMmon prompt, issue the xmodem command. However, before you issue the xmodem
command, ensure that you have the new Cisco IOS software image on your PC.
In this example, all Flash memory is erased before downloading using the f option (only on the Cisco
1600 Series ). Perform a CRC−16 checksum using the c option and using a download speed of
115200 bps (only on the Cisco 1600 Series ) by specifying −s115200:
rommon 12 >xmodem −cfs115200 c1600−sy−mz.121−16.bin
Do not start the sending program yet...
Note: If the console port is attached to a modem, both the console port and the modem must be
operating at the same baud rate.
Use console speed 115200 bps for download [confirm]
File size Checksum File name
1957444 bytes (0x1dde44) 0xe345 c1600−y−mz.113−9.T
Erasing flash at 0x83f0000 no partition 2 on device: PCMCIA slot 1
Ready to receive file c1600−sy−mz.121−16.bin ...
Download will be performed at 115200.
make sure your terminal emulator is set to
this speed before sending file.
Warning:
All existing files in the partition displayed and files in any
other partitions on this device will be lost! Continue ? press 'y'
for yes, 'n' for no:y
2.
Configure the terminal emulator program for a data rate of 115200 bps to match the xmodem speed
specified above. This is done by closing the previous terminal session of 9600 bps and opening a new
one at 115200 with 8−N−1. The trick here is that the Cisco 1603 only supports a maximum baud rate
of 9600 bps. Therefore, when connecting at 115200 bps, you cannot see the router prompt. This is an
important point to remember. Once connected to the router at 115200 bps, select Transfer and Send
File from the HyperTerminal menu bar.
3.
4. Specify the image file name and location and enter xmodem as the protocol.
5. Click on Send to start the transfer.
This message is received when the transfer is complete:
Download Complete!
Returning console speed to 9600
Please reset your terminal emulator to this speed...
Per the message above, you need to exit your 115200 bps HyperTerminal session and restart a new
one at 9600 bps. Once connected, the router's ROMmon prompt appears. Verify that the download
was successful by issuing a dir flash:.
rommon 9 >dir flash:
File size Checksum File name
3686656 bytes (0x384100) 0x1a5e c1600−sy−mz.121−16.bin
6.
Change the config register back to 0x2102 and reset or power cycle the router so that the new Cisco
IOS software image gets loaded.
rommon 10 >confreg 0x2102
You must reset or power cycle for new config to take effect.
rommon 11 >reset
System Bootstrap, Version 12.0(19981130:173850) [rameshs−120t_lava 114],
DEVELOPMENT SOFTWARE Copyright (c) 1994−1998 by cisco Systems, Inc.
Simm with parity detected, ignoring onboard DRAM
C1600 platform with 16384 Kbytes of main memory
program load complete, entry point: 0x4020060, size: 0x15568c
%SYS−6−BOOT_MESSAGES: Messages above this line are from the boot loader.
program load complete, entry point: 0x2005000, size: 0x3840e0
Self decompressing the image : ########################################
################
........
Cisco Internetwork Operating System Software
IOS (tm) 1600 Software (C1600−SY−M), Version 12.1(16),
RELEASE SOFTWARE (fc1)
Copyright (c) 1986−2002 by cisco Systems, Inc.
Compiled Mon 08−Jul−02 17:09 by kellythw
Image text−base: 0x02005000, data−base: 0x0275BD48
7.
.......
Xmodem Procedure for Downloading a Cisco IOS Software
Image onto a Cisco 2620 Router
Use this xmodem procedure in order to download a Cisco IOS software image onto a Cisco 2620 Router.
Launch a terminal emulator program.
This example Windows HyperTerminal is configured for 8−N−1 at 9600 bps. Connect your PC's
****** port to the console port of the router. Once connected, get into the ROMmon prompt (rommon
1>). Typically, if the router's Cisco IOS software image and bootflash image are both corrupt, the
router only comes up in ROMmon mode. If the former is not true and you need to get into the
ROMmon prompt, then you will need to change the configuration register (typically 0x2102 as given
by show version) to 0x0 as follows:
2620#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
2620(config)#con
2620(config)#conf
2620(config)#config−register 0x0
2620(config)#^Z
2620#
5d03h: %SYS−5−CONFIG_I: Configured from console by console
2620#
2620#reload
System configuration has been modified. Save? [yes/no]: n
Proceed with reload? [confirm]
5d03h: %SYS−5−RELOAD: Reload requested
System Bootstrap, Version 11.3(2)XA4, RELEASE SOFTWARE (fc1)
Copyright (c) 1999 by cisco Systems, Inc.
TAC:Home:SW:IOS:Specials for info
C2600 platform with 65536 Kbytes of main memory
rommon 1 >
1.
Once in ROMmon, change the console baud rate from 9600 bps to 115200 bps to speed up the
download time. Use the confreg command and complete the instructions presented on the screen.
rommon 1 >confreg
Configuration Summary
enabled are:
break/abort has effect
console baud: 9600
boot: the ROM Monitor
do you wish to change the configuration? y/n [n]: y
enable "diagnostic mode"? y/n [n]:
enable "use net in IP bcast address"? y/n [n]:
enable "load rom after netboot fails"? y/n [n]:
enable "use all zero broadcast"? y/n [n]:
disable "break/abort has effect"? y/n [n]:
enable "ignore system config info"? y/n [n]:
change console baud rate? y/n [n]: y
enter rate: 0 = 9600, 1 = 4800, 2 = 1200, 3 = 2400
4 = 19200, 5 = 38400, 6 = 57600, 7 = 115200 [0]: 7
change the boot characteristics? y/n [n]:
Configuration Summary
enabled are:
2.
break/abort has effect
console baud: 115200
boot: the ROM Monitor
do you wish to change the configuration? y/n [n]:
You must reset or power cycle for new config to take effect.
rommon 2 >
Once the router boots up in ROMmon, the HyperTerminal sessions start to display illegible
characters. You need to exit the current terminal session and start a new one at a data rate of 115200
bps to match the console rate as in step 2.
3.
You are now ready to issue the xmodem command. However, before issuing the xmodem command,
ensure that you have the new Cisco IOS software image on your PC.
rommon 1 >
rommon 1 >xmodem −?
xmodem: illegal option −− ?
usage: xmodem [−cyrx] <destination filename>
−c CRC−16
−y ymodem−batch protocol
−r copy image to dram for launch
−x do not launch on download completion
rommon 2 >
rommon 2 >
rommon 2 > xmodem −c c2600−is−mz.122−10a.bin
!−−− Note that [−s datarate] is not available here since you are set for 115200 bps.
Do not start the sending program yet...
File size Checksum File name
9939820 bytes (0x97ab6c) 0x4991 c2600−is−mz.122−7a.bin
Warning:
All existing data in bootflash will be lost!
Invoke this application only for disaster recovery. Do you wish to continue?
y/n [n]: y Ready to receive file c2600−is−mz.122−10a.bin ...
4.
From the HyperTerminal menu bar, select Transfer > Send and specify the image name/location and
xmodem protocol as in steps 3 and 4 and start the transfer.
5.
Once the transfer is complete, these messages appear:
Erasing flash at 0x60fc0000
program flash location 0x60990000
Download Complete!
Notice how the Flash gets erased towards the end automatically compared to Cisco C1600. Therefore,
the reason why the f option is not required here. Finally, ensure that you reset the console speed back
to 9600 and change the boot sequence back to default by changing the configuration register back to
0x2102:
rommon 12 > confreg 0x2102
You must reset or power cycle for new config to take effect
rommon 2 >reset
System Bootstrap, Version 11.3(2)XA4, RELEASE SOFTWARE (fc1)
Copyright (c) 1999 by cisco Systems, Inc.
TAC:Home:SW:IOS:Specials for info
C2600 platform with 65536 Kbytes of main memory
program load complete, entry point: 0x80008000, size: 0x995ec8
Self decompressing the image : ################################
################################################## ################
################################################## ################
######################## [OK]
............................
Cisco Internetwork Operating System Software
IOS (tm) C2600 Software (C2600−IS−M), Version 12.2(10a), RELEASE SOFTWARE (fc1)
6.
Copyright (c) 1986−2002 by cisco Systems, Inc.
Compiled Tue 21−May−02 14:16 by pwade
Image text−base: 0x80008088, data−base: 0x810ABB08
cisco 2620 (MPC860) processor (revision 0x100) with 61440K/4096K bytes of memory.
Processor board ID JAB03110MUB (3691217154)
M860 processor: part number 0, mask 49
Bridging software.
X.25 software, Version 3.0.0.
1 FastEthernet/IEEE 802.3 interface(s)
2 Voice FXS interface(s)
32K bytes of non−volatile configuration memory.
16384K bytes of processor board System flash (Read/Write)
Press RETURN to get started!
.........................
Xmodem Procedure for Downloading a Cisco IOS Software
Image onto a Cisco 3600 Router
Use this xmodem procedure in order to download a Cisco IOS software image onto a Cisco 3600 Series
Router.
The standard procedure uses the default console speed of 9600 bits per second. Xmodem is a slow transfer
protocol, and the transfer of a file as large as a Cisco IOS software image could take an unacceptably long
time. An increase to the console speed on the 3600 router helps decrease the time it takes to do the xmodem
file transfer.
When in ROMMON mode, complete this procedure using the ROMMON confreg utility.
rommon 2 > confreg
do you wish to change the configuration? y/n [n]: y
enable "diagnostic mode"? y/n [n]: n
enable "use net in IP bcast address"? y/n [n]: n
disable "load rom after netboot fails"? y/n [n]: n
enable "use all zero broadcast"? y/n [n]: n
enable "break/abort has effect"? y/n [n]: n
enable "ignore system config info"? y/n [n]: n
change console baud rate? y/n [n]: y
enter rate: 0 = 9600, 1 = 4800, 2 = 1200, 3 = 2400
4 = 19200, 5 = 38400, 6 = 57600, 7 = 115200 [7]: 7
change the boot characteristics? y/n [n]: y
enter to boot:
0 = ROM Monitor
1 = the boot helper image
2−15 = boot system
[0]: 0
Configuration Summary
enabled are:
load rom after netboot fails
console baud: 115200
boot: the ROM Monitor
do you wish to change the configuration? y/n [n]: n
You must reset or power cycle for new config to take effect
rommom 2 > reset
1.
Open a new hyperterminal with these settings:
Bits per second − 115200
2.
Data bits − 8
Parity − None
Stop bits − 1
Flow control − Hardware
After setting the hyperterminal, you receive a rommon prompt. Enter the xmodem command. Before
you enter an xmodem command, there should be a software image residing in your terminal or your
local hard drive.
rommon 2 > xmodem −c c3640−i−mz.121−7.bin
Do not start the sending program yet...
File size Checksum File name
4936800 bytes (0x4b5460) 0x2dd7 c3640−i−mz.121−7.bin (bad checksum: 0x13eb)
WARNING: All existing data in flash will be lost!
Invoke this application only for disaster recovery.
Do you wish to continue? y/n [n]: y
Ready to receive file c3640−i−mz.121−7.bin ...
3.
After this message appears, you have to download the file using xmodem and this procedure:
a. Go to Hyperterminal and click the Transfer menu.
b. Select Send File.
In the dialog box which appears, click on browse and look for the file name on your local
hard drive.
c.
d. Under the filename field is the Protocol drop−down box. Choose Xmodem.
e. Click Send to initiate the file transfer.
4.
After the transfer completes, the router will reload itself. When the reload completes, press the return
key to be taken to a prompt and to reset the configuration register and the console line speed.
Router> enable
Router#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#configure terminal
Router(config)#config−register 0x2102
Router(config)#line con 0
Router(config−line)# speed 9600
5.
Upon changing the console speed, you will lose connectivity. Go to your terminal program, change
the baud rate to 9600, and reconnect to the router console.
Router(config−line)#ctrl z
Router #write mem
Router #reload